Medical practitioners utilize a variety of gastro-intestinal devices to access the gastro-intestinal tract. One type of gastro-intestinal device, the gastro-intestinal tube, is widely used with patients who require catheterization for the purposes of, for example, delivering food or medication to the gastro-intestinal tract, draining the tract, or creating a surgical port. Patients with damage to their upper gastro-intestinal tract, or with neurological or mental impairment often need long-term catheterization for these purposes. In order to place catheters within the gastro-intestinal tract, medical practitioners often use Percutaneous Endoscopic Gastrostomy (PEG) techniques. These techniques typically involve either placing a gastro-intestinal tube in the patient's mouth and snaking it down the esophagus, into the stomach, and out the abdominal wall, or they involve inserting the tube into the stomach from outside of the abdominal wall by sliding the tube over a guidewire.
Gastro-intestinal tubes, like other gastro-intestinal devices which provide access to the gastro-intestinal tract, typically have an internal bolster, or anchoring device, at one end which secures the tube within the stomach. When the tube is properly placed, the end having the bolster lies inside the stomach wall. The tube is pulled from outside the abdomen until the internal bolster forces the stomach against the abdominal wall; a process called "approximation." An additional bolster is often placed on the outside of the abdominal wall to hold the stomach in contact with the abdominal wall. After the stomach and abdominal wall are held in place for approximately two weeks, a fistulous tract, called a stoma, forms which runs from the stomach to the outer surface of the abdominal wall.
When using percutaneous gastrostomy, practitioners face several common complications, including: infection at the stoma site, premature tube removal, and tube migration. Peristomal infections, the most common post-placement complication, result from introducing a gastro-intestinal tube into the sterile abdominal penetration, after the tube has been dragged through non-sterile locations such as the mouth, esophagus, and the external abdominal wall. Although prophylactic medication often prevents infection, peristomal infection still occurs in a small percentage of cases where prophylactic treatment has been administered.
Most gastro-intestinal tubes used in long-term catheterization remain in place for several months. During that time, the tubes are manipulated by medical practitioners who clean the stoma site, attach and detach devices for delivering food and medicine, and otherwise move the tubes. The tubes are also manipulated by patients, some of whom suffer from mental or neurological disorders and try to remove the tube by pulling it from outside the abdominal wall. Such manipulation can cause the tube to become misplaced within or removed from the gastro-intestinal tract.
If the tube is deliberately or inadvertently pulled before the stoma forms, it may fall out of the stomach wall and become misplaced either within the abdominal wall or within the peritoneal cavity which is sterile and susceptible to infection. Since peritoneal infection often goes unnoticed until it has become severe, misplacing the tube within that cavity can cause serious medical complications. If the tube is pulled after the stoma has formed, it may be completely removed from the stoma, requiring replacement procedures. The internal bolster may also rupture the stomal tract as it is pulled through, requiring subsequent medical procedures.
Tube migration refers to post-placement tube movement within the stomach and abdominal walls. Migration typically results from clamping the outer bolster too tightly against the abdomen during approximation. Excessive clamping pins the internal bolster tightly against the stomach wall, often leading to ulceration and necrosis of the gastric tissue. As the tissue dies or is displaced, the bolster migrates into the body tissue. Because PEG approximation is usually performed without endoscopic visualization, the excessive clamping often goes undetected.
If migration occurs before the stomal tract forms, the bolster may become misplaced within the peritoneal cavity. Migration into the peritoneal cavity often leads to severe infection and, where the tube is used for feeding or medication delivery, to misdirected delivery into the peritoneal cavity. Tube migration often goes undetected until observable manifestations, such as bleeding, occurs.
A high incidence of tube migration occurs where flexible internal bolsters are used. Although such bolsters enable tube removal by pulling the tube from outside the abdominal wall, they are also more susceptible to tube migration. When outer bolsters are used in connection with flexible internal bolsters and clamped tightly, the flexible internal bolster may be pulled into the abdominal penetration. Due to their flexible structure of these flexible bolsters, they often migrate further into the penetration.
Another common complication from using percutaneous gastrostomy relates to deliberate tube removal by medical personnel. Gastro-intestinal tubes often become occluded or clogged and must be removed and replaced. They are also periodically removed and replaced during normal medical maintenance. Some tubes have rigid internal bolsters which prevent removal by pulling from outside the abdominal wall. These bolsters must be removed either surgically or by endoscopic snare. Other tubes have internal bolsters which detach when the tube is traction pulled, and are left to be expelled from the body through excretion. These additional invasive procedures increase patient discomfort, risk of infection, as well as medical expenses.
Applied Medical Technologies, Inc. of Independence, Ohio markets a device called the "Secure Cath Adaptor" having a rigid disk which fits over the tube shaft, up against a more flexible internal bolster. The rigid disk is designed to prevent removal by pulling the tube from outside the abdominal wall; called removal by traction pull or traction removal. Thus, in addition to preventing premature traction removal, the disk prevents traction removal for tube replacement. The "Secure Cath Adapter" tube must then be removed by using an endoscopic snare, an invasive and often expensive medical procedure. Practitioners may nevertheless attempt traction removal, as such removal is often performed without internal visualization. In the process, the stomal tract may be damaged.
The prior art contains several gastro-intestinal tubes which inhibit premature removal to some degree while allowing deliberate removal by medical personnel. U.S. Pat. No. 5,356,391 describes a tube with a collapsible internal bolster. During normal operation, the bolster retains its domed shape. During traction pull, the dome collapses to a diameter which allows the bolster to pass through the stoma. A similar device is described in U.S. Pat. No. 5,391,159. U.S. Pat. No. 5,248,302 describes an internal bolster which can be removed through use of an obturator.